Rapid advances in nucleic acid determination have led to questions about the secondary and tertiary structure of DNA and RNA. It is clear now that the sequence alone of a nucleic acid is not sufficient to determine many of the processing and control functions. Computer techniques have been developed by others for experimentally determining the pairing of nucleic acid bases. This project has developed a technique for displaying the two-dimensional structure of general nucleic acid sequences. Two-dimensional diagrams for the 16S fragment of the ribosome (1.6 kilo bases) have been generated. A complete language for input, manipulation and display of nucleic acid two-dimensional structures has been developed. Copies of the program package have been exported to other institutions. An attempt has been made to synthesize the three-dimensional structure of general nucleic acid sequences. Because crystallography has been done on only a few nucleic acid structures (straight helix DNA and RNA, and two tRNA's) the critical insights needed for general structure synthesis are still missing. Modeling techniques are being developed to solve this problem.